To ask the Secretary of State for Defence whether a decision has been taken to retrofit the Vanguard Class Ballistic Missile Submarines with a Combat Management System based upon Microsoft Windows 2000; and if he will make a statement.

No decision has been made on whether to modify the Combat Management System onboard Vanguard Class Submarines, to enable the system to operate on Microsoft's Windows 2000 software. However, an independent review concluded that Windows 2000 operating software, when used in conjunction with the original application software, is both safe and secure. As a result, some Trafalgar Class submarines are being modified to incorporate Windows 2000 into the Tactical Command System, which is used in the launch process for Spearfish torpedoes and Tomahawk missiles.